Correcting for discretionary treatment crossover in an analysis of survival in the Breast International Group BIG 1-98 trial by using the inverse probability of censoring weighted method.

摘要

The authors of the accompanying article should be commended for a clear and thoughtful investigation of the survival comparison of letrozole and tamoxifen from the data of the BIG 1-98 trial. This major breast cancer trial showed a statistically significant disease-free survival (DFS) advantage for patients randomly assigned to letrozole, but this did not translate into a significant overall survival (OS) advantage, possibly because of the impact of a crossover by patients using tamoxifen therapy to letrozole therapy when evidence of benefit on DFS was released. While the treatment crossover may have been necessary on ethical grounds, it left the scientific audience with an uncertainty about whether letrozole could offer a survival advantage.